1. Field of the Invention
The present invention relates to a device for measuring the brake torque in a vehicle undercarriage in which the brake torque is transmitted to said vehicle undercarriage by a bar-shaped member and said bar-shaped member is loaded transversely by said brake torque. The invention further relates to a sensor for such a device.
2. Prior Art
The brakes of aircraft include stacks of mutually interleaved brake disks that are pressed against each other by hydraulic or electric actuators. One of the stacks is connected to the respective wheel. The other stack is connected to the stationary part of the landing gear for receiving the brake torque. In order to transmit the brake torque, i.e. the torque that appears when the brakes are activated, to the landing gear, the latter stationary stack is non-rotatably locked to the landing gear in a suitable manner. Generally, this is achieved by a fastening device that is arranged on the stationary stack eccentrically with respect to the axis of the wheel, in the simplest case a bore. A bolt serves for connecting the stationary stack to the landing gear directly or via a torque takeout arm. This bolt is highly stressed by the torque in the transverse direction and is consequently made of a high-strength material. Since its diameter is generally relatively large, it is hollow in order to reduce its weight.
For various reasons it is desirable to measure the momentary braking action. To this end, U.S. Pat. No. 4,474,060 suggests designing the bushing that is normally arranged between the mentioned bolt and the respective receiving opening, as a torque sensor. However, the disadvantage of this solution is that it involves a modification of the elements which serve for force transmission, thereby causing considerable expenditures for the certification of this solution. The certification is relatively time-consuming and costly and may furthermore be required, in the extreme case, for each aircraft type separately.
Similar problems in the measurement of the brake torque may also be encountered in other types of vehicles whose braking systems are similar to those of aircraft.